Looping through an NSMutableArray

I have a NSMutableArray that I load up with different objects (classes).

Now I need to go through the array and get to the classes for further manipulation.

I was trying this approach...

for (id obj in allPointsArray)   
  {
///// 开发者_Go百科  this is where i need to bring the obj into a class to work with
    NSInteger loc_x = obj.x_coord;
    NSInteger loc_y = obj.y_coord;
  }

but I cannot get my head around actually bringing the class out of the array and placing it into a usuable object.

the x_coord and y_coord are common between all of the objects stored in the array.

Thanks for everyone help

---

Are you trying to do different things if the objects in the array are of different classes? You could do something like this:

for (id obj in myArray) {
    // Generic things that you do to objects of *any* class go here.

    if ([obj isKindOfClass:[NSString class]]) {
        // NSString-specific code.
    } else if ([obj isKindOfClass:[NSNumber class]]) {
        // NSNumber-specific code.
    }
}

---

The code should work if you use the message syntax instead of the dot one:

for (id obj in allPointsArray) {
    NSInteger loc_x = [obj x_coord];
    NSInteger loc_y = [obj y_coord];
}

Or you could write a common protocol for all your points:

@protocol Pointed
@property(readonly) NSInteger x_coord;
@property(readonly) NSInteger y_coord;
@end

@interface FooPoint <Pointed>
@interface BarPoint <Pointed>

Now you could narrow the type in the iteration and use the dot syntax:

for (id<Pointed> obj in allPointsArray) {
    NSInteger loc_x = obj.x_coord;
    NSInteger loc_y = obj.y_coord;
}

Depends on the context.

---

You can use the -isKindOfClass: instance method of NSObject to inspect your objects for class membership. Thusly:

for (id obj in allPointsArray) {
    if ([obj isKindOfClass:[OneThing class]]) {
        OneThing* thisThing = (OneThing *)obj;
        ....
    }
    else if ([obj isKindOfClass:[OtherThing class]]) {
        OtherThing *thisThing = (OtherThing *)obj;
        ....
    }
}

If you do it that way, not only will it compile, but Xcode will suggest helpful code completions based on the class you're casting thisThing to.